Design a smoking questionnaire to be given to all subjects who are given a multi-phasic health check-up. At the fourth month, twelve male and twelve female subjects will be given tests for expired air CO levels and serum thiocyanate concentration. At the end of the first year, a random sampling of 10% of the subjects will be mailed a tobacco questionnaire to estimate changes in ssmoking habits and estimate the number of days of incapacitation due to minor illnesses. Outpatient records will be searched. Hospitalization data and vital statistics will be obtained. Mortalitydata will be obtained during the last three months of the contract.